2 files changed, 67 insertions, 22 deletions

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 4af939a00e54..4753a1831dbc 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -64,6 +64,7 @@
 #include <linux/libata.h>
 #include <asm/semaphore.h>
 #include <asm/byteorder.h>
+#include <linux/cdrom.h>
 
 #include "libata.h"
 
@@ -4652,6 +4653,43 @@ int ata_check_atapi_dma(struct ata_queued_cmd *qc)
 }
 
 /**
+ *      atapi_qc_may_overflow - Check whether data transfer may overflow
+ *      @qc: ATA command in question
+ *
+ *      ATAPI commands which transfer variable length data to host
+ *      might overflow due to application error or hardare bug.  This
+ *      function checks whether overflow should be drained and ignored
+ *      for @qc.
+ *
+ *      LOCKING:
+ *      None.
+ *
+ *      RETURNS:
+ *      1 if @qc may overflow; otherwise, 0.
+ */
+static int atapi_qc_may_overflow(struct ata_queued_cmd *qc)
+{
+        if (qc->tf.protocol != ATA_PROT_ATAPI &&
+            qc->tf.protocol != ATA_PROT_ATAPI_DMA)
+                return 0;
+
+        if (qc->tf.flags & ATA_TFLAG_WRITE)
+                return 0;
+
+        switch (qc->cdb[0]) {
+        case READ_10:
+        case READ_12:
+        case WRITE_10:
+        case WRITE_12:
+        case GPCMD_READ_CD:
+        case GPCMD_READ_CD_MSF:
+                return 0;
+        }
+
+        return 1;
+}
+
+/**
  *      ata_std_qc_defer - Check whether a qc needs to be deferred
  *      @qc: ATA command in question
  *
@@ -5139,23 +5177,19 @@ static void atapi_send_cdb(struct ata_port *ap, struct ata_queued_cmd *qc)
  *      Inherited from caller.
  *
  */
-
-static void __atapi_pio_bytes(struct ata_queued_cmd *qc, unsigned int bytes)
+static int __atapi_pio_bytes(struct ata_queued_cmd *qc, unsigned int bytes)
 {
         int do_write = (qc->tf.flags & ATA_TFLAG_WRITE);
-        struct scatterlist *sg = qc->__sg;
-        struct scatterlist *lsg = sg_last(qc->__sg, qc->n_elem);
         struct ata_port *ap = qc->ap;
+        struct ata_eh_info *ehi = &qc->dev->link->eh_info;
+        struct scatterlist *sg;
         struct page *page;
         unsigned char *buf;
         unsigned int offset, count;
-        int no_more_sg = 0;
-
-        if (qc->curbytes + bytes >= qc->nbytes)
-                ap->hsm_task_state = HSM_ST_LAST;
 
 next_sg:
-        if (unlikely(no_more_sg)) {
+        sg = qc->cursg;
+        if (unlikely(!sg)) {
                 /*
                  * The end of qc->sg is reached and the device expects
                  * more data to transfer. In order not to overrun qc->sg
@@ -5164,21 +5198,28 @@ next_sg:
                  *    - for write case, padding zero data to the device
                  */
                 u16 pad_buf[1] = { 0 };
-                unsigned int words = bytes >> 1;
                 unsigned int i;
 
-                if (words) /* warning if bytes > 1 */
-                        ata_dev_printk(qc->dev, KERN_WARNING,
-                                       "%u bytes trailing data\n", bytes);
+                if (bytes > qc->curbytes - qc->nbytes + ATAPI_MAX_DRAIN) {
+                        ata_ehi_push_desc(ehi, "too much trailing data "
+                                          "buf=%u cur=%u bytes=%u",
+                                          qc->nbytes, qc->curbytes, bytes);
+                        return -1;
+                }
+
+                 /* overflow is exptected for misc ATAPI commands */
+                if (bytes && !atapi_qc_may_overflow(qc))
+                        ata_dev_printk(qc->dev, KERN_WARNING, "ATAPI %u bytes "
+                                       "trailing data (cdb=%02x nbytes=%u)\n",
+                                       bytes, qc->cdb[0], qc->nbytes);
 
-                for (i = 0; i < words; i++)
+                for (i = 0; i < (bytes + 1) / 2; i++)
                         ap->ops->data_xfer(qc->dev, (unsigned char *)pad_buf, 2, do_write);
 
-                ap->hsm_task_state = HSM_ST_LAST;
-                return;
-        }
+                qc->curbytes += bytes;
 
-        sg = qc->cursg;
+                return 0;
+        }
 
         page = sg_page(sg);
         offset = sg->offset + qc->cursg_ofs;
@@ -5213,19 +5254,20 @@ next_sg:
         }
 
         bytes -= count;
+        if ((count & 1) && bytes)
+                bytes--;
         qc->curbytes += count;
         qc->cursg_ofs += count;
 
         if (qc->cursg_ofs == sg->length) {
-                if (qc->cursg == lsg)
-                        no_more_sg = 1;
-
                 qc->cursg = sg_next(qc->cursg);
                 qc->cursg_ofs = 0;
         }
 
         if (bytes)
                 goto next_sg;
+
+        return 0;
 }
 
 /**
@@ -5268,7 +5310,8 @@ static void atapi_pio_bytes(struct ata_queued_cmd *qc)
 
         VPRINTK("ata%u: xfering %d bytes\n", ap->print_id, bytes);
 
-        __atapi_pio_bytes(qc, bytes);
+        if (__atapi_pio_bytes(qc, bytes))
+                goto err_out;
         ata_altstatus(ap); /* flush */
 
         return;
diff --git a/include/linux/libata.h b/include/linux/libata.h
index cb91280be9bd..124033cb5e9b 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -119,6 +119,8 @@ enum {
         ATA_DEF_BUSY_WAIT       = 10000,
         ATA_SHORT_PAUSE         = (HZ >> 6) + 1,
 
+        ATAPI_MAX_DRAIN         = 16 << 10,
+
         ATA_SHT_EMULATED        = 1,
         ATA_SHT_CMD_PER_LUN     = 1,
         ATA_SHT_THIS_ID         = -1,